Professor Peter Dayan won the Brain Prize in 2017, together with Ray Dolan and Wolfram Schultz, “for their pioneering work on the neural mechanisms of learning and reward and the influence of these on human behavior”.

What Counts as a Decision?

Almost every action that you do originally came from some decision process that happened in your brain. This includes, for example, choosing what to wear this morning, whether to go to school by foot or by bus, and whether to play soccer or read a book in the break between classes. In fact, people go through the world constantly making decisions. At the smallest level, it could be said that even “choosing” which muscles to activate every fraction of a second when you walk is a kind of a decision. But, on a more practical, everyday level, the decisions that interest us are higher-level decisions that control whole sequences of actions people do. These higher-level decisions could be mundane things like deciding whether you go left or right at the end of the corridor to get out of your house, or whether to walk vs. run to the bus station. But they could also be longer-term and more consequential, such as what school to attend, or even whom (if anyone) to go out with.

Decision making is one of the most critical things that people do. On a basic level, people must make good decisions to survive. Good decisions also help people to live prosperous, satisfying lives. The great importance of decision making is also reflected in the brain, where much of this organ is devoted to the process. Many systems and brain regions participate in decision making, including those associated with memory, planning, emotions, and action control [1]. Due to the great complexity of decision making, scientists have not yet found a complete “circuit” in the brain that allows them to explain exactly how a particular decision was made. Nonetheless, there are some very interesting principles that govern how people make decisions.

Fast Or Comfortable?

Most of the decisions people make are not fully conscious. Even some of the choices you believe you make deliberately often have unconscious roots. Take buying a car: there are many factors to consider, such as looks, speed, safety, fuel efficiency, environmental impact, and comfort. A perfect decision maker would weigh all of these factors and choose the car that best balances them. In reality, people usually focus on just one or at most couple of factors at a time—like speed can comfort—and base their choice on those, without integrating them fully (Figure 1). This may seem deliberate, but was prioritizing speed over safety or comfort truly a conscious decision? Most likely not; it probably reflects an unconscious bias, meaning a preference that the person is not even aware of [1]. Even if someone explains their preference after the fact, such as “I enjoy passing other cars”, the deeper reasons for that bias are still at least partly unconscious.

This simple car-buying example demonstrates two important aspects of decision making—one is that it has an unconscious aspect to it, and the other is that often there are many factors people should consider to make the best overall decision, but they frequently consider only a small subset of these—which may lead to a decision that is not the best one. Decisions are also complex because some of them unfold over long periods of time, and it is difficult to figure out whether one choice is better than another. For example, was going to the school you are currently in a better decision than going to school in another town? In most cases, this decision is made only once and there is no way for a trial and error-type of learning to take place—so there is no direct and simple way to test the quality of the decision (for further reading on decision processes, you can read this and this FYM article).

Dopamine: The Choice Teacher

Despite the complexity of the decision-making process, the brain has what is, at least at first sight, a surprisingly simple and straightforward mechanism that influences decision making. You can think of this mechanism sort of like the “carrot and stick” strategy of the brain, which makes people repeat decisions that have beneficial outcomes and reduce decisions with undesired outcomes. This mechanism involves a substance called dopamine [2] (for more information on how dopamine rewards work, see this FYM article).

Dopamine is a chemical messenger used as a signal that teaches us how to make better choices. To manage in the world, your brain must constantly make predictions about the consequences of your actions. So, for every action you do, your brain “guesses” what the action’s outcome will be. Many times, there is a difference between what the brain predicted would happen and what really happened. This gap is called a prediction error [3, 4]. When things turn out better than you expected—which is called a positive prediction error—you experience a burst of dopamine (the “carrot”). This makes you repeat the same action again, and it also teaches you to adapt your expectation (in this case, to expect a better result) the next time you perform the same action. If, on the other hand, things turn out worse than expected and you experience a negative prediction error (the “stick”), and you will feel discouraged and lower your expectations for the next time you face the same choice.

For example, let us say you studied for an exam for 1 h and expected to get a “C” but you actually got a “B”. This creates a positive prediction error—you will feel very happy, and this might make you want to learn more for the next exam, expecting to get a “B” or higher. If, on the other hand, you studied for 1 h, expected to get a “B”, but actually got a “D”, you will probably feel disappointment and lower your grade expectation for the next exam (Figure 2). Through the dopamine mechanism, your brain is constantly trying to decrease prediction error, teaching you to make better decisions in the future based on what you learned from past decisions.

Dopamine and Addiction

It is important to note that the teaching signal of dopamine in the brain can also go wrong, and lead to addiction [2]. Simplifying matters, addiction seems to start when artificially large amounts of dopamine are released in the brain as a result of an activity. Such activities are often potentially harmful, such as drugs, but maybe also more apparently innocuous things such as social media scrolling or eating processed foods (Figure 3). When dopamine is released through these actions, it mimics what happens during a positive prediction error and makes you want to repeat the action again. You might want to keep doing an action even when you do not really like it any more or it makes you feel bad [5]. For example, you might have an urge to keep scrolling through social media even though you are very tired and scrolling is no longer enjoyable. In these cases, it is important to find ways to “fix” the dopamine mechanism to work in your favor instead of creating harmful consequences. For instance, you could start paying close attention to when and why you start scrolling and try to change the habit so that it does not become an automatic, semi-unconscious behavior.

When Decisions Go Wrong—And How to Make Them Better

Sometimes decision making goes wrong, as we saw with addiction. It can be useful to try and categorize how this can happen, to improve understanding and ultimately to offer advice or treatment [6]. One category is that the brain might be trying to solve the wrong problem—for example, if we no longer like any of the things we used to, then we might become listless and apathetic. A second is that it might attempt to use the wrong solution, even though it is trying to solve the right problem—for example failing to avoid wolfing down a delectable-looking cream bun, despite being committed to a diet. Third, the decisions can be suitable, but for an environment that is no longer relevant. For instance, someone who grew up in a bullying environment may continue to expect danger even after moving to a safe and friendly school. In all these cases, past experiences or habits guide decisions in ways that no longer fit the present situation.

To make better decisions, it helps to first tell apart choices that really matter from those that do not. Small decisions, like choosing an ice cream flavor, can be quick and impulsive. Bigger, long-term decisions deserve more thought. A useful strategy is to list the important factors involved and think carefully about the ones that matter most to you. It also helps to imagine your future self—picture how you might feel months or years from now as a result of your choice. Making this future feel real can give you a better perspective and help you choose in ways that benefit you in the long run. Just like learning a sport or an instrument, decision making is a skill—and the more you practice it, the better you get at it!

Glossary

Conscious: ↑ Describes thoughts or actions that are done deliberately, like making a choice after carefully thinking through the options.

Bias: ↑ A “shortcut” your brain takes that can make you prefer one choice over another, even when it is not the best option.

Trial and Error: ↑ Trying something out, seeing what happens, and then changing what you do until you get the result you want.

Dopamine: ↑ A brain chemical that helps you learn which choices are good or bad, by giving you a signal when something turns out better or worse than you expected.

Prediction Error: ↑ The difference between what you expected to happen as the result of a decision and what actually happened.

Addiction: ↑ When dopamine “highs” makes you keep repeating an activity—even if it no longer feels good, or causes harm.

Conflict of Interest

OR declared that they were a contractor of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision.

The remaining author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Acknowledgments

We wish to thank Iris Gat for providing the figures, and Susan Debad for copyediting the manuscript. PD was supported by the MAX Planck Society and the Humboldt Foundation.

Additional Materials

• The Brain Prize 2017 – Learning and Reward

• Why Choose This Book?: How We Make Decisions

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